Help:Diagrams

This wiki can store diagrams as diagrams rather than as uploaded pictures. A diagram lives on its own page, keeps a full edit history like any other page, and can be re-opened and changed by the next person — no hunting for the original file, and no re-uploading a flat image every time something moves.

You need to be logged in and in the writer group to create or change a diagram. Anyone can view them.

Choosing a format

Namespace	Best for	How you edit it
Mermaid:	Flowcharts, sequence diagrams, state machines, ER diagrams, timelines	Text — a few lines of Mermaid syntax
DOT:	Graphs and trees: signal chains, network maps, workflows	Text — Graphviz DOT syntax
Drawio:	Free-form drawings, block diagrams, anything you want to drag around	Full visual editor (draw.io / diagrams.net)
BPMN:	Formal process diagrams, with elements that can link to wiki pages	Visual editor
Gantt:	Project schedules with dependencies	Visual editor

Mermaid and DOT are the two most useful here for typical hardware, RF and reverse-engineering documentation, and they are the easiest to review in a diff because the source is plain text.

Creating a diagram

The easiest way is to write a red link and click it:

On any page, add a link in a diagram namespace, for example [[Mermaid:Meter capture chain]].
Save, then click the new red link.
The diagram editor opens directly. Fill it in and save.

You can also go straight to the editor for a page that does not exist yet by visiting its URL with ?action=editdiagram on the end.

On a diagram page that already exists, use the Edit diagram tab at the top.

Showing a diagram on another page

Diagram pages are not transcluded with the usual double braces. Use Template:Diagram, naming the diagram page including its namespace:

{{Diagram|page=Mermaid:Meter capture chain}}

That renders the diagram inline wherever you put it, so an article can show a diagram that is maintained on its own page. Each section below gives the exact line for that format's example.

You do not have to type any of that. In the visual editor, diagrams can be added, repointed and opened for editing without touching wikitext — see Using the visual editor below.

The older form {{#display_diagram:Mermaid:Meter capture chain}} still works and renders identically. Prefer the template: #display_diagram is a parser function, and the visual editor can edit a template's parameters but not a parser function's target, so bare calls can only be changed by editing the page source.

Highlighting one node for one page: Mermaid diagrams take an optional style parameter that restyles part of the diagram on that page only — see Highlighting part of a diagram on one page.

One limit to know about: a single page can contain at most one BPMN or Gantt diagram — the extension gives both of them the same internal element name, so a second one on the same page is refused with an error message. Mermaid, DOT and Drawio can be embedded as many times as you like.

Using the visual editor

Screenshots for this section have not been uploaded yet. Each caption below names the file to upload — for example FlexDiagrams VE insert template.png — so uploading under that exact name fills the slot with no further edit to this page.

Everything here works in the ordinary visual editor. Nothing below requires editing wikitext.

Adding a diagram to a page

Put the cursor where the diagram should go, then Insert → Template. Type Diagram and choose it.

File:FlexDiagrams VE insert template.png

The Insert → Template dialog with "Diagram" typed into the search box.

Fill in the Diagram page field with the diagram's full page name, including its namespace prefix — Mermaid:, DOT:, Drawio:, BPMN: or Gantt:. The field suggests existing pages as you type, so you rarely need to type the whole name.

File:FlexDiagrams VE diagram field.png

The Diagram page field, suggesting existing diagram pages as you type.

Insert, and save the page as usual.

What a diagram looks like while editing

An embedded diagram does not appear as a picture in the visual editor. It shows as a single labelled line naming the diagram, like:

◈ Mermaid:RE FlowChart Overview — diagram, edit it on its own page

File:FlexDiagrams VE placeholder.png

An embedded diagram as it appears while editing: one labelled line rather than the rendered picture.

That is deliberate. The visual editor cannot run the diagram renderer, so without it you would see the diagram's raw source — dozens of lines of flowchart code — sitting in the middle of the article. The line above is shown instead. Save or preview the page to see the diagram itself.

Editing the diagram

Double-click the line. The diagram's own editor opens in a new tab, leaving your article edit untouched in the original tab. Edit the diagram, save it there, then return to your article.

Changing which diagram is shown

Single-click the line to select it. A small box appears with two choices:

Edit "…" ↗ — opens that diagram's editor in a new tab, the same as double-clicking.
Change which diagram is shown — opens the template's settings so you can point this embed at a different diagram page.

File:FlexDiagrams VE context menu.png

Selecting an embedded diagram: edit the diagram itself, or change which diagram the page shows.

Single-clicking also selects the diagram as a block, so Backspace removes the embed from the article — which deletes only the embed, never the diagram page itself.

If you edit the source instead

The visual editor is not required. In the source editor the same embed is one line:

{{Diagram|page=Mermaid:RE FlowChart Overview}}

Both editors produce exactly the same thing, and you can move between them freely.

Mermaid

Flowcharts, sequence diagrams, state machines, class and ER diagrams, pie charts and timelines, all written as text. Served entirely from this wiki.

Example page: Mermaid:Example diagram — open it in the editor

Its source is simply:

flowchart LR
    A[Smart meter] -->|900 MHz| B(SDR capture)
    B --> C{Decodes?}
    C -->|yes| D[rtlamr output]
    C -->|no| E[Adjust gain / freq]
    E --> B

Embed it in a page with:

{{Diagram|page=Mermaid:Example diagram}}

which renders as:

flowchart LR A[Smart meter] -->|900 MHz| B(SDR capture) B --> C{Decodes?} C -->|yes| D[data output] C -->|no| E[Adjust gain / freq] E --> B

See the Mermaid documentation for the full syntax. This wiki bundles Mermaid 11.17.2, so the Mermaid 11 diagram types — architecture, packet, kanban, treemap and radar — all work. Diagram types added in Mermaid 12 will not render, and layout: elk is not available (it falls back to the default layout silently).

How diagrams are styled

Mermaid diagrams on this wiki use the RECESSIM theme, set once site-wide, so every diagram looks the same without anyone having to style it: grey nodes with red borders, black connectors, and grey subgraph containers. You do not need to do anything to get it.

Two pages exist to check the theme, because a diagram page holds exactly one diagram:

Mermaid:Theme test — every node shape, link style and nested subgraph.

 Open in the editor

Mermaid:Theme test pie — a pie chart, which is the one diagram type whose

 colours come from secondaryColor and tertiaryColor rather
 than the node colours. Open in the editor

Open both after any change to the site-wide theme to check nothing has broken.

Which shape means what

Mermaid:Theme test labels every shape with its meaning and the syntax that produces it, so it doubles as a cheat-sheet. Mermaid reaches only 14 shapes through the classic bracket syntax; the rest need A@{ shape: doc } form, which is where the standard flowchart symbols live — document, manual input, display, delay, loop limit, stored data and so on.

Three shapes are used differently here than in Mermaid's own documentation, so go by this wiki, not by the Mermaid docs:

Stadium ([text]) — start and end of a flow.
Circle ((text)) — a connector, as in traditional

 flowcharts. Mermaid's docs call this "Start"; we do not.

Double circle (((text))) and the asymmetric shape

 >text] have no agreed meaning here. Mermaid itself describes the
 asymmetric one only as "Odd shape". They are on the test page for reference; do not use
 them to mean anything.

For the same reason, avoid the rounded rectangle (text) and the small/framed circles — Mermaid assigns them Event, Start and Stop, which collide with the stadium above. The test page marks all of these.

A diagram can override the theme for itself, with either a %%{init: ...}%% directive or a YAML config: block at the top of its source. Be aware that doing so makes that diagram ignore the site-wide theme completely, including any later change to it — so prefer leaving it alone unless one diagram genuinely needs to differ.

Highlighting part of a diagram on one page

An article sometimes needs to point at one step of a shared diagram without changing the diagram itself. Add a style parameter to Template:Diagram: its contents are added to the end of the diagram for this embed only. The diagram page, and every other page that shows it, stay exactly as they are.

{{Diagram|page=Mermaid:RE Microscope Workflow|style=style MW_Memory_File stroke-width:8px}}

flowchart LR MW_Memory_File((IC Data)) MW_Sample-Preparation[Sample Preparation] subgraph MW_Optical-Extraction [Optical Microscope]; end subgraph MW_Electron-Extraction [Electron Microscope]; end MW_Sample-Preparation --> MW_Optical-Extraction --> MW_Memory_File MW_Sample-Preparation --> MW_Electron-Extraction --> MW_Memory_File %% ___ added by this embed ___ style MW_Memory_File stroke-width:8px

Compare it with the unmodified Mermaid:RE Microscope Workflow: only the IC Data circle has changed. In the visual editor, the same thing is the Extra style (Mermaid only) field of the template.

Use the node's id, not its label. Above, the id is MW_Memory_File; its label is IC Data. Open the diagram page to find the ids.
Several statements go on one line, separated by ;, e.g. style=style MW_Memory_File stroke-width:8px; style MW_Sample-Preparation fill:#ffd
Any Mermaid flowchart statement works, not only style — e.g. classDef hot fill:#ffd; class MW_Memory_File,MW_Sample-Preparation hot to highlight several nodes the same way.
A misspelled id is not reported. Mermaid does not complain — it draws an extra, empty node with that name. If a stray box appears, check the spelling.
Mermaid only. On a DOT, Drawio, BPMN or Gantt page the parameter shows an error instead of the diagram.
Editing the diagram page still updates this embed by itself, with no purge.

Building one diagram from several pages

A large flowchart can be split up so that each part is its own diagram page — with its own editor, preview and history — while an overview page assembles them into a single diagram at render time. Edit a part and every overview that uses it updates by itself, with no purge.

Here are two small parts. Mermaid:Example part one:

flowchart LR
  EX1_Start([Start]) --> EX1_Capture[/Capture signal/]
  EX1_Capture --> EX1_Decode[Decode frames]

flowchart LR EX1_Start([Start]) --> EX1_Capture[/Capture signal/] EX1_Capture --> EX1_Decode[Decode frames]

and Mermaid:Example part two:

flowchart LR
  EX2_Analyse[Analyse payload] --> EX2_Report[[Write it up]]
  EX2_Report --> EX2_End([End])

flowchart LR EX2_Analyse[Analyse payload] --> EX2_Report[[Write it up]] EX2_Report --> EX2_End([End])

Put them together on any ordinary page with <composediagram>. Each part gets an id, a title (the heading shown on its box) and the page to read. Edges joining the parts go between the tags:

<composediagram direction="TD"
 id1="EX_Capture"  title1="Capture"  page1="Mermaid:Example part one"
 id2="EX_Analysis" title2="Analysis" page2="Mermaid:Example part two">
EX_Capture --> EX_Analysis
</composediagram>

which renders as:

flowchart TD %% ___ begin Mermaid:Example part one ___ subgraph EX_Capture [Capture] direction LR EX1_Start([Start]) --> EX1_Capture[/Capture signal/] EX1_Capture --> EX1_Decode[Decode frames] end %% ___ end Mermaid:Example part one ___ %% ___ begin Mermaid:Example part two ___ subgraph EX_Analysis [Analysis] direction LR EX2_Analyse[Analyse payload] --> EX2_Report[[Write it up]] EX2_Report --> EX2_End([End]) end %% ___ end Mermaid:Example part two ___ %% ___ edges between parts ___ EX_Capture --> EX_Analysis

A worked example with five parts is at User:Hash/Sandbox.

Choosing how deep to draw

Add level to draw every part at a given depth, or levelN to set part N on its own (it overrides level):

Level	What each part shows
`1`	One block with the part's title
`2`	The part's own nodes; any subgraphs inside it are drawn as titled blocks
`3`, `4`, …	One more layer of subgraphs opened at each step

<composediagram direction="TD" level="1" level5="3" ...>

With no level at all, every part is drawn in full, exactly as before. Setting a part to all (e.g. level5="all") also means full depth, which is useful when level sets a lower default.

Empty subgraphs are placeholders — subgraph FW_Advanced [Advanced Techniques]; end — and simply stay blocks at any level until someone fills them in. No error.
Edges into hidden nodes are redrawn to the block that now stands for them, keeping their labels, so the overview's edges can point at nodes deep inside a part and still make sense when that part is collapsed.
Contents must be written inline in the part page; a subgraph cannot pull in another page.

Examples of each are at User:Hash/Sandbox#Depth levels.

What you need to get right

Each part must be a valid diagram on its own, starting with flowchart .... That header is removed when composing (it is not legal inside a subgraph) but its direction is kept, so a part laid out LR still runs left-to-right inside the overview.
Node ids must be unique across every part. This is the one that bites. Give each part its own prefix — EX1_, EX2_, FI_, ME_. If two parts both declare Start, Mermaid does not report an error: it silently merges the two boxes, keeping the position of the first and the label of the last, so one part quietly starts displaying another part's text. The tag checks for this before rendering and, if it finds a clash, shows an error naming the id and both pages instead of drawing a misleading diagram.
Edges that join two parts belong in the overview, between the tags — a part cannot refer to ids it does not contain.
Do not put a config: or %%{init}%% block in a part. It is stripped when composing, and on the part's own page it would override the site-wide theme (see #How diagrams are styled).
The subgraph id you choose shares the same namespace as the node ids, so it must not collide with a node in any part either.

If a part has a syntax error, the overview is what shows the error. The composed source carries %% ___ begin <Page> ___ markers, so the line number in the error message can be traced back to the part that caused it.

DOT

Graphviz DOT source, rendered in your browser by the bundled Viz.js. You describe what connects to what and Graphviz works out the layout. Served entirely from this wiki.

Example page: DOT:Example diagram — open it in the editor

Its source:

digraph FlashExtraction {
    rankdir=LR;
    node [shape=box];
    "Target PCB" -> "Desolder chip";
    "Desolder chip" -> "Socket adapter";
    "Socket adapter" -> "Programmer";
    "Programmer" -> "Binary dump";
    "Binary dump" -> "Analysis";
}

Embed it in a page with:

{{Diagram|page=DOT:Example diagram}}

which renders as:

digraph FlashExtraction { rankdir=LR; node [shape=box]; "Target PCB" -> "Desolder chip"; "Desolder chip" -> "Socket adapter"; "Socket adapter" -> "Programmer"; "Programmer" -> "Binary dump"; "Binary dump" -> "Analysis"; }

Drawio

The full draw.io drawing tool, for free-form diagrams you build by dragging shapes around. Good when the layout itself carries meaning — panel layouts, wiring sketches, block diagrams.

Example page: Drawio:Example diagram — open it in the editor

Embed it in a page with:

{{Diagram|page=Drawio:Example diagram}}

which renders as:

One thing to know: the Drawio editor is loaded from the external site embed.diagrams.net while you are editing. Your diagram is saved here on the wiki, not on their servers, and viewing a saved Drawio diagram does not contact them at all — but editing one needs that external site reachable from your browser. The other four formats are served entirely from this wiki.

BPMN

Formal business-process diagrams, drawn with bpmn-js. Worth knowing: an element named [[Some page]] becomes a link to that wiki page, so a process diagram can double as navigation.

Example page: BPMN:Example diagram — open it in the editor

Embed it in a page with:

{{Diagram|page=BPMN:Example diagram}}

which renders as:

That embed uses this page's one BPMN-or-Gantt slot; a second diagram of either type on the same page would be refused.

Gantt

Project schedules with tasks, durations and dependencies, drawn with dhtmlxGantt. Useful for planning a long teardown or a multi-stage project on its own page.

Example page: Gantt:Example diagram — open it in the editor

Embed it in a page with:

{{Diagram|page=Gantt:Example diagram}}

This help page cannot show that live: it already embeds a BPMN diagram above, and only one BPMN-or-Gantt diagram is allowed per page (see above). To see it rendered, open Gantt:Example diagram itself.

Tips

Diagrams are ordinary pages: History, Talk, watchlisting and the normal backups all apply.
Because Mermaid and DOT are text, their page histories produce readable diffs — prefer them over an uploaded image when the diagram is likely to change.
Give diagrams descriptive names, the same as files — Mermaid:Landis Gyr Focus teardown steps beats Mermaid:Diagram 3.
The five example pages above are meant to be edited and experimented with. If you want a scratch diagram of your own, make a new page rather than overwriting an example.

Help:Diagrams

Contents

Choosing a format

Creating a diagram

Showing a diagram on another page

Using the visual editor

Adding a diagram to a page

What a diagram looks like while editing

Editing the diagram

Changing which diagram is shown

If you edit the source instead

Mermaid

How diagrams are styled

Which shape means what

Highlighting part of a diagram on one page

Building one diagram from several pages

Choosing how deep to draw

What you need to get right

DOT

Drawio

BPMN

Gantt

Tips

See also

Navigation menu

Help:Diagrams

Choosing a format

Creating a diagram

Showing a diagram on another page

Using the visual editor

Adding a diagram to a page

What a diagram looks like while editing

Editing the diagram

Changing which diagram is shown

If you edit the source instead

Mermaid

How diagrams are styled

Which shape means what

Highlighting part of a diagram on one page

Building one diagram from several pages

Choosing how deep to draw

What you need to get right

DOT

Drawio

BPMN

Gantt

Tips

See also

Navigation menu

Search